Deuterium gas on demand - on th' cheap

[Richard Hull]

Gerado Meiro's post immediately prior to this got the wheels turning.

Here is the total deal

D20 has an atomic weight of 20, therefore, 20 grams or approx 20ml of D20 will, if properly and perfectly electrolized, produce one mole of Deuterium or D2 gas and 1/2 mole of O2 gas. The O2 we just don't care about.

One mole of D2 gas, or any gas for that matter, is 22.4 liters at STP or about 24 liters at common room temperature.

The foregoing was stated by Gerado in his post. Some of you might not know the chemistry of it all so I elaborated above.

Gas use:

As the fusor operates at about 10 microns that is about 100,000th of an atmosphere. A six inch fusor is just over 1.5 liters. Thus, a liter of D2 is enough for 60,000 fills!!! Of course, with flowing gas, this figure might be cut to only 5,000 runs. Thus 20 grams of heavy water might make about 100,000 fusor runs. Again, With the average fusioneer, and his poorer gas handling system, this final figure might be cut in half. So you see, it is a baby's micro breath of D2 that is needed.

Now to make up our D2 on demand system:

First, we have to get electrodes.

There are only two real choices that won't screw with the chemistry of what we are trying to do. Platinum or Carbon. Let us go with pure carbon due to costs.

Now, the heavy water needs an ion to allow the electrolysis. I had a discussion with Kevin Dunn our groups resident PhD chemistry professor. We settled on Sodium Carbonate (washing soda). You will get some CO2, yes, but bear with me.

Washing soda is cheap and found in many hardware or even well stocked grocery stores. It is non-toxic and non threatening. You must dry it first, however. Place the amount you will need in an oven at high heat for several hours and then immediately place the amount required into the D2O. We figure under 1 gram is needed in 50ml of D2O.

From here it is now a matter of collecting the D2 gas over the heavy water and taking it via a piece of glass tubing to a coiled tube in a small container of liquid nitrogen. This will freeze out any water or heavy water vapor as well as any CO2 gas. What exits is dry D2 gas.

From here, we might desire a small reservoir tank. (Old used up CO2 cartridge is good) Valves to isolate the tank from the generator system and vacuum system would be nice, too.

The output of the small tank might go to a needle valve or mass flow controller directly to the fusor.

The plumbing, valving and the need for liquid N2 at every run might negate the cost savings over the valve and run operation of a D2 cylinder purchased for about $200 with a regulator extra $$$.

I really like the idea of making the D2 as needed in very small amounts.

Postscript.

Really clean sodium (about 200 mg. ) could be dropped into the heavy water to be electrolized and the resultant minor D2 gas realease would be nice, but you would then have a very friendly NaOD ion system freeing you from the sodium carbonate drill.

Always thinking.


Richard Hull

[Tom Dressel]

Richard:

I have read that at room temperature palladium can absorb 900 times its own volume of hydrogen (probably a siimilar amount of deuterium). At a density of 12.2 gm/cm3, one ounce will absorb over a liter of deuterium

Would it be possible to electrochemically load a small amount of palladium with deuterium, (exclusive of D2O), place it in a side chamber, and then bleed it into the main chamber via a needle valve? This may require heating the palladium. This would have the advantage of storing a large quanity of dry deuterium, essentially in the solid state, to be delivered at will.

The other question: is it possible to ELECTROSTATICALLY load palladium with deuterium, by placeing a ball of palladium in the center of a fusor inner grid and applying DC current in a deuterium atmasphere?

Tom Dressel

[Richard Hull]

Yes, palladium can be loaded either electrocheically (best way) or electrostatically (surface loading only). Heating will release the gas. This use to be used in the arms of low vacuum gas x-ray tubes around the turn of the last century. An old x-ray technician would know just the right amount of gas to release as the tube "hardened" to restore operation.

Unfortunately, the palladium to store a single liter would cost, realistically, about 450.00/oz and it would come as an ingot. The market price of palladium has actully dropped to about $350.00, but you'll pay an extra hundred to buy it from one of the few metals brokers who mess with small orders. The price a couple of years ago was over $1200.00/oz!! The melting temperature of paladium is far too high (1550 deg C.)for remelting and casting into shapes at the amateur level. I note that Alpha Aesar still wants over $1000.00/ounce in slug form at only 998 purity. Most 1 oz. ingots on the open metals market are a minimum of 999 pure.

The above lowest price would buy about two cylinders of D2 gas. Wisely used, these would last two lifetimes of the average fusioneer.

Bottom line....my recommendation is.......if you gotta' decent job, buy a nice 50 or 75 liter cylinder and be done with it. If you have a lot of toys that will let you economically generate your own D2 by electrolizing heavy water or are poor and seek to cobble every thing up from scratch then by all means, use skill and cunning to avoid cash outlays.

Me? I have two cylinder of D2 and haven't even dented the first one yet with all my fusor activity.

Richard Hull

[Starfire]

Richard, if I wish to construct a Palladium membrane barrier in a gas line, can you advise on which solder I can use on a Paladium foil 0.1 mm [ about 10mm sq ] -- I want to seal the foil in line.

[Richard Hull]

As long as the line and membrane are not getting hot, I would use a 50:50, Sn:In solder. I use this all the time to solder or join glass to glass, glass to metal and ceramics. Its very low melting point is great and its strength is about 4 times that of pure indium.

Needless to say, heat that thin a foil indirectly with a well controlled soldering iron.

Richard Hull

[Starfire]

Tks Richard,
Dare I ask where can I get the 50:50, Sn:In solder ?

[Richard Hull]

I offer the 50:50 alloy in my trading post area. I distribute it in easy to use and remelt disks about the size of a U.S. gold dollar coin but about 1/4" thick. Current prices $15.00/ounce plus shipping additional (~$1.50).

Richard Hull